Back-sprayed laminates with a colored layer are in principle already known (see for example DE 44 24 106 A), as are high temperature-resistant printing inks (DE 198 32 570 A1 and DE 44 21 561 A1 and the publication by the Pröll company, Treuchtlinger Str. 29, 91781 Weiβenburg published in November 1999 entitled “Einführung in die IMD-Technologie”. The laminates according to DE 44 24 106 A1 have serious disadvantages however that are not mentioned in DE 44 24 106 A1, nor are any remedial methods and measures indicated there. The employed films that are mentioned there can expand only to a small extent and have to be thermoformed in a complicated intermediate step by vacuum or high pressure cold forming after preheating. This step leads to an unnecessary stress of the thermoplastic material and to a deterioration of the mechanical properties of the film. By using polycarbonate-based films the resultant product is softer and has a better feel, though parts having a high abrasion resistance cannot be obtained. The areas of application of decorated laminates are restricted. The polyurethane layers have to be applied from aqueous dispersion or from organic solvents, which is an unnecessary intermediate step according to the present invention since an intermediate layer serving as adhesive is not required. The thermoplastic material layers mentioned in DE 44 24 106 A1 have to be sprayed on at high temperatures (>260° C.), which in the case of the laminates according to the prior art necessitates the use of the aforementioned intermediate layer, since without the latter the colored layer would suffer from washing-out and distortion.
There is therefore a need to simplify significantly the production of decorated laminates and to open up further, hitherto inaccessible areas of application.
The laminates described in DE 44 24 106 A1 also have a high Shore hardness.
It has surprisingly been found that laminates based on films of thermoplastic polyurethanes with particularly low Shore hardnesses can be produced without any problem.
It has furthermore been found that a preforming step (thermoforming) is not necessary since on account of its extremely high expansibility the film can be adapted as required to any given geometrical shape.
It has moreover been found that, in contrast to the Pröll Company publication, the printing ink also adheres to thermoplastic TPU films.